High Ca + Low Alk

[Neon Reefer]

I've been dosing kalk for about a year now since I moved away from one part acetates due to the cost of them. My tank is what I would classify as a moderately high supplement demand tank with all stony corals.

Since moving to kalk I have had a real issue with maintaining Good Alk levels. Besides dosing the Kalk I also supplement with dosing pumps. My plan was to dose the Kalk in equities to maintain the Ca and supplement the Alk and Mg with dosing pumps.

I kept increasing the kalk over time to get the Ca to 450ppm which is where I always kept my tank. Eventually I reached the max amount of kalk I could dissolve ( 1 cup per five gals water) thru my ATO and was using about 7 - 8 gals per week. Was needing to dose ca as well to keep up with demand and stay at 450ppm. During that time I was dosing baking soda per R Farley's recipe for the Alk and could never get it above ~ 7.0 dKH. I kept upping the dosing of Alk and the numbers kept dropping.

Then one day my numbers seemed to get really funky. Ca upwards of 750ppm and Alk down to low 6s. I purchased new testing equipment (Red Sea Pro) and got same numbers. I had RCA verify the numbers and they got the same thing. Ca double natural seawater and Alk in the mid sixes. All along my Mg has been a little low. I like to keep it at 1500 and it was around 1350ppm so no worries. Currently it is a little low at 1250ppm

So what I did a couple of weeks ago is stopped dosing kalk altogether and only continued with the Alk dosing and Mg dosing, which I upped by about 20% each. I continued to do my 10 gals weekly water change with Kent salt and changed my Alk supplement to BRS soda ash.

So that's the background on my situation. And after 2.5 weeks of change my numbers have changed only a small amount. Ca from 780 to 720ppm and Alk up only to high sixes. Mg is pretty steady at 1250ppm. Is it normal to only change this small amount or should it be faster. Is there something else going on here or what. When I manually dose the Alk to make sure the Alk pump is working I do notice some snow affects. But no accumulation on pumps or heaters.

Thru it all my corals are healthy and showing good growth. My fish seem normal.

[FarmerTy]

I suspect your super saturated Calcium level is causing immediate precipitation of any alk added if I had to take a guess... But its been awhile since I've had to diagnose any reef chemistry issues between the foundation elements.

If it were me, I'd do water changes until my Ca level was below 550 ppm, which will probably put your alk level back in line as well. At that point, resume your independent dosing of Ca and Alk through the dosers.

[Neon Reefer]

So you'd guess I am seeing Alk precipting out and not Ca precipting out

[FarmerTy]

So you'd guess I am seeing Alk precipting out and not Ca precipting out

One in the same in a typical reef scenario. The precipitate is calcium carbonate and is the combination of calcium and the carbonate (alk). My memory of the interactive processes between the foundation elements are fuzzy though so don't take anything I say to the bank. Haha.

The only thing keeping your super high Ca from causing a snowstorm of precipitate is your Mg right now. If your Mg starts dropping below say 1200 ppm or 1100 ppm, it could set off a chain reaction and you'll end up with a cloudy mess of a tank. I'd just do some simple water changes to bring your Ca and alk levels in line and then tweak it to your desired levels from that point on.

[Sascha D.]

I'm not sure which Randy Holmes-Farley article you're referencing, but I use this one. I haven't had to fix many imbalances because I keep my levels close to natural seawater, but I've had success using water changes and the method described below.

Understanding how to fix imbalances in calcium and alkalinity is an important skill for all reef aquarists. Often aquarists must use methods other than their ordinary supplement method to fix imbalances. For example, if calcium is low (say, 300 ppm) and alkalinity is normal (say, 3 meq/L), no amount of tweaking of limewater or CaCO₃/CO₂ reactors can solve the problem. Using any balanced method to boost calcium by 120 ppm will boost alkalinity by 6 meq/L (16.8 dKH). Such a large boost in alkalinity will normally result in precipitation of calcium carbonate, and will preclude a useful boost in calcium.

The most important tools for fixing imbalances are an “alkalinity only” supplement (such as grocery store baking soda or a commercial buffer) and a “calcium only” supplement (usually calcium chloride, such as Dowflake, or a commercial calcium supplement). These two types of supplement allow aquarists to boost one and not the other. Please note that despite its confusing label, Tropic Marin Biocalcium is a balanced calcium and alkalinity supplement, so it cannot be used to make substantial corrections to low calcium levels.

[Reburn]

Not trying to be short just not into mucho typing tonight. This is explained in simple Laymens terms for my benefit to avoid typing too much.

First stop dosing at all.

You have an ionic imbalance caused by an overdose of Ca. Kalk is a pretty balanced dosing solution. You way over did it. You shouldn't have dosed ca too. Your tank will not fix itself. The only thing keeping your tank from snowing is your realitivity high MG level. The bond between mg/alk Is very fragile. Which allows the mg/alk elements to break apart. Alk/Ca bond is permanent in the form of white percipitation. It will literally look like snow and drop your alk to the ground. Do 25% water changes every 3 days until your levels match the fresh saltwater. After your tank is back to natural levels don't dose at all until you see a 0.5 dkh day drop. Then I would restart Kalk very slow. Like a TEAspoon a gallon. While your getting your dosing sorted out dose daily tropic Marin biocalcium to maintain alk levels. Don't dose ca. It's properly balanced in the Kalk and biocalcium.

[Reburn]

Also my cardinal rule.

Don't ever use your dosing system to adjust levels. Always and only by hand dosing. A Doser, CaRx or Kalk should only be used to maintain levels. Never to adjust them

[Neon Reefer]

I'm not sure which Randy Holmes-Farley article you're referencing, but I use this one. I haven't had to fix many imbalances because I keep my levels close to natural seawater, but I've had success using water changes and the method described below.

Understanding how to fix imbalances in calcium and alkalinity is an important skill for all reef aquarists. Often aquarists must use methods other than their ordinary supplement method to fix imbalances. For example, if calcium is low (say, 300 ppm) and alkalinity is normal (say, 3 meq/L), no amount of tweaking of limewater or CaCO₃/CO₂ reactors can solve the problem. Using any balanced method to boost calcium by 120 ppm will boost alkalinity by 6 meq/L (16.8 dKH). Such a large boost in alkalinity will normally result in precipitation of calcium carbonate, and will preclude a useful boost in calcium.

The most important tools for fixing imbalances are an “alkalinity only” supplement (such as grocery store baking soda or a commercial buffer) and a “calcium only” supplement (usually calcium chloride, such as Dowflake, or a commercial calcium supplement). These two types of supplement allow aquarists to boost one and not the other. Please note that despite its confusing label, Tropic Marin Biocalcium is a balanced calcium and alkalinity supplement, so it cannot be used to make substantial corrections to low calcium levels.

I believe this is what I am doing. Besides doing the 15% weekly water changes I stopped dosing kalk at together and am only dosing pure alk in the form of soda ash and dosing mg The numbers are slowly falling but very slowly. Ca has fallen to 650 and Alk remains in the mid sixes. I also have noticed an explosion of Coraline Algea.which makes the low Alk even more difficult to deal with.